1. Field of the Invention
The present invention relates to method for manufacturing thin film transistors (TFTs).
2. General Background
In recent years, efforts have been made to form high-performance semiconductor elements on an insulating substrate such as a glass substrate or on an insulating film. The successful manufacture of such components can realize the commercial production of items such as a large-scale liquid crystal display device with high resolution, a monolithic liquid crystal display device with a driver circuit formed on the same substrate for cost reduction, a fit-type image sensor with high speed and high resolution, and a three-dimensional integrated circuit (IC). As a semiconductor element, a thin film transistor using a silicon semiconductor thin film as an active region is generally used for these kinds of devices.
A typical method for manufacturing a TFT is summarized in FIG. 7. The method includes the steps of: providing a substrate; cleaning the substrate; forming a metal film on the substrate; coating the substrate with a photo-resist layer, and exposing and developing the photo-resist layer; etching the substrate; and finally removing the remainder of the photo-resist layer using one or more suitable solutions.
One or desired layers to be formed on a substrate may include an active layer, a gate electrode, and/or a source/drain electrode. When each layer is formed, a base material and a photo-resist layer need to be deposited on the substrate. Then, the photo-resist layer is exposed and developed to form a photo-resist pattern. Finally, the base material is etched using the photo-resist pattern as a mask. That is, deposition equipment, exposing equipment, developing equipment, and etching equipment are all necessary, and the process for manufacturing a TFT is complicated and costly.
Therefore, a new method for manufacturing a TFT that can overcome the above-described problems is desired.